The commit is pushed to "branch-rh7-3.10.0-327.22.2.vz7.16.x-ovz" and will
appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.22.2.el7
------>
commit e2b27e0eb71646fac108ba71fc02e60de2c89ea6
Author: Konstantin Khlebnikov <[email protected]>
Date: Wed Jul 27 17:05:48 2016 +0400
ms/sched/fair: Initialize throttle_count for new task-groups lazily
ms commit: 094f469172e00d6ab0a3130b0e01c83b3cf3a98d
Cgroup created inside throttled group must inherit current throttle_count.
Broken throttle_count allows to nominate throttled entries as a next buddy,
later this leads to null pointer dereference in pick_next_task_fair().
This patch initialize cfs_rq->throttle_count at first enqueue: laziness
allows to skip locking all rq at group creation. Lazy approach also allows
to skip full sub-tree scan at throttling hierarchy (not in this patch).
Signed-off-by: Konstantin Khlebnikov <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: [email protected]
Link:
http://lkml.kernel.org/r/146608182119.21870.8439834428248129633.stgit@buzz
Signed-off-by: Ingo Molnar <[email protected]>
https://jira.sw.ru/browse/PSBM-50099
Signed-off-by: Andrey Ryabinin <[email protected]>
---
kernel/sched/fair.c | 20 ++++++++++++++++++++
kernel/sched/sched.h | 2 +-
2 files changed, 21 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 515685f..b6f70a3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3850,6 +3850,26 @@ static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
if (!cfs_bandwidth_used())
return;
+ /* Synchronize hierarchical throttle counter: */
+ if (unlikely(!cfs_rq->throttle_uptodate)) {
+ struct rq *rq = rq_of(cfs_rq);
+ struct cfs_rq *pcfs_rq;
+ struct task_group *tg;
+
+ cfs_rq->throttle_uptodate = 1;
+
+ /* Get closest up-to-date node, because leaves go first: */
+ for (tg = cfs_rq->tg->parent; tg; tg = tg->parent) {
+ pcfs_rq = tg->cfs_rq[cpu_of(rq)];
+ if (pcfs_rq->throttle_uptodate)
+ break;
+ }
+ if (tg) {
+ cfs_rq->throttle_count = pcfs_rq->throttle_count;
+ cfs_rq->throttled_clock_task = rq_clock_task(rq);
+ }
+ }
+
/* an active group must be handled by the update_curr()->put() path */
if (!cfs_rq->runtime_enabled || cfs_rq->curr)
return;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 2bdf80b..d9fe825 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -352,7 +352,7 @@ struct cfs_rq {
u64 throttled_clock, throttled_clock_task;
u64 throttled_clock_task_time;
- int throttled, throttle_count;
+ int throttled, throttle_count, throttle_uptodate;
struct list_head throttled_list;
struct list_head boosted_entities;
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